In software engineering, an entity–relationship model (ER model) is a data model for describing the data or information aspects of a business domain or its process requirements, in an abstract way that lends itself to ultimately being implemented in a database such as a relational database. The main components of ER models are entities (things) and the relationships that can exist among them. This article refers to the techniques proposed in Peter Chen's 1976 paper. However, variants of the idea existed previously, and have been devised subsequently such as supertype and subtype data entities and commonality relationships.

UML is an enhanced form of OMT and thus an enhanced form of the ER model1 (
Ou, 1997). Although object-oriented methods enjoy some success in the software
development field, software engineers often turn to ER diagrams and relational ...

The structure of a database can be represented by using an entity-relationship diagram. Many extensions have been made to the ER approach to improve its
usefulness as a database design tool. In [14], a normal form for ER diagrams was
...

The class diagram models classes in the real world and specifies the
relationships between them. The underlying concept of class diagrams may
seem to be similar to that of ER diagrams; however, there are a few fundamental
differences ...